Hydrogeochemistry as a Tool for Platinum Group Element (PGE) Exploration – A Case Study from Sittampundi Anorthosite Complex, Southern India

Abstract

The use of surface and ground water for exploration of platinum group elements (PGE) has been studied in the Sittampundi anorthosite complex, Tamil Nadu, south India, where PGE mineralization is known to occur in basic and ultrabasic rocks. Groundwater interacting with mineralized rocks creates a geochemical signature which can be linked to the occurrence and distribution of PGE, especially Pd because of its leachability and relatively high mobility in aqueous environment. Forty surface and ground water samples collected from the area were analyzed for PGE and several other major, minor and trace elements using high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS) to investigate the distribution patterns of individual PGE and other elements for the purpose of evaluating the utility of hydrogeochemistry as a tool for PGE exploration studies. Ground and surface water chemistry reflected the chemical composition of host lithology, particularly the basic-ultrabasic rocks of the region, with the dispersion of PGE and high anomalous concentrations of Pd, Ru and Rh along with several other metals such as Zn, V, Cr and Ni indicating PGE mineralization. The results of this study suggest that groundwater chemistry has significant potential as a PGE exploration tool with advantages such as rapid and low-cost sampling, high contrast anomalies and a uniform sampling medium.

Indicator Minerals, Pathfinder Elements, and Portable Analytical Instruments in Mineral Exploration Studies

“…For example, critical aspects, such as the geological setting, rock types, minerals, pathfinder element enrichments, the drainage patterns, and the geophysical signatures, must favor identifying a deposit. Recent studies indicated that groundwater is an important medium for the geochemical exploration of different styles of mineralization, including those of PGE, gold, and uranium [37][38][39]. Modern commercial miniature devices are commonly lighter than two kilograms and can be used in the field with ease [40].…”

“…In general, the concept is based on the interaction between groundwater and the mineralized zone and the leaching of trace/heavy metals under favorable pH-Eh conditions. The sub-surface recharge of groundwater results in the greater likelihood of rock-water interaction with buried mineralization compared to surface geochemical methods [39]. LED fluorimetry comprises the steps of exciting the uranyl ion in the sample by using electromagnetic energy of suitable wavelengths and measuring the decay with time of the uranium phosphorescence after the termination of the incident electromagnetic radiation.…”

Current and emerging analytical techniques for geochemical and geochronological studies

“…Hydrogeochemical prospecting techniques are increasingly being applied in uranium, gold, and PGE exploration studies (Balaram et al, 2019;Giblin & Snelling, 1983;Narayanaswamy, Ramkumar, & Anjaiah, 1998). Geochemical mapping programs are currently being utilized in various socio-economic developmental programmes, including delineation of target zones for enhanced potential through reconnaissance stage investigations (Bhat, Singh, Bhat, Nath, & Guha, 2019).…”

“…Groundwater chemistry is largely a function of mineral composition of the rock formation through which it flows due to water-rock interactions. Water is also used as medium of sampling during mineral exploration studies, because ores and minerals have an effect on the composition of water through dissolution (Balaram et al, 2019;Narayanaswamy et al, 1998). Proper guidelines for the collection of representative water samples are well described in the literature (e.g., Myers, 2006).…”

“…Several metals are stable at lower pH, and higher concentration of protons will also hinder metal absorption/adsorption. It has been proved that preservation of metals within water sample by acidification to a pH <2 effectively stabilizes the metal concentration for 180 days (Balaram et al, , 2019.…”